Organization of the POSIX/iX Library

The POSIX/iX library

The POSIX/iX library file, /lib/libc.a, contains four classes of C library functions:

The POSIX/iX math library

The POSIX/iX math library consists of additional mathematical functions, such as trigonometric and logarithmic functions, that perform floating-point operations. These math library functions perform in a manner defined by ANSI C.

	NOTE: It is recommended that you use the POSIX/iX math library when developing applications using the MPE/iX Developer's Kit.

The common usage math library

The common usage math library consists of the same library functions available in the POSIX/iX math library; however, common usage math library functions perform in a pre-ANSI manner that does not conform to either ANSI C or the POSIX.1 standard.

The primary difference between the two math libraries is the manner in which errors are handled, such as attempting to compute the square root of a negative value. POSIX/iX math library behavior causes the library to call a user-written function named _matherr if one is provided, and no error message is displayed. Common usage math library behavior causes the library to call a user-written function named matherr if one is provided; otherwise, an error message is displayed.